Data Analysis

As part of the TOGA upper ocean observing system, a network of XBT sections was established in 1983-1986 along commercial shipping lines between the western coast of Australia and various ports (Meyers et al., 1995; Meyers, 1996; Wijffels and Meyers, 2004). The lines investigated are detailed in Fig. 3 and are designated: IX1 that is from Fremantle on the southwest coast of Australia to Sunda Strait on the western tip of Java, Indonesia; and PX2 that crosses the Banda Sea just north of the Lesser Sunda island arc. On all lines, Sippican T-4 and T-7 XBTs were dropped roughly every 4h (~80nm) from volunteer observing vessels. Sampling has occurred on average at fortnightly frequency along IX1 and monthly frequency on the other lines, though it can be less due to changes in shipping and the time required to re-equip the line. In mid-1986, the probe type changed from Sippican T-4s to T-7s and thus after this date, the maximum depth of the profiles collected changed from 450m to 760m. The profiles were carefully quality controlled (Bailey et al., 1994); further details can be found in Wijffels and Meyers (2004). Wind stresses applied to observational data to explore wave dynamics were derived from the NCEP reanalysis described by Kalnay et al. (1996) as downloaded from the Climate Diagnostic Center, Boulder, USA. Altimetric sea-level data from AVISO are also used (Le Traon et al., 1998).

Figure 3: Locations ofWOCE XBT profiles used in this study. The names of the primary lines and plots are indicated. Water depths shallower than 200 m are grey shaded.

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